System and method for recycling organic-inorganic composite sheet

ABSTRACT

A system and method for recycling a workpiece comprises an electrolytic etching assembly for etching a metal layer of the workpiece. The electrolytic etching assembly has an electroetching unit, a working stage, a power supply and an electrolyte source supply. The electroetching unit has an anode, a cathode next to the anode and an insulting covering, wherein the cathode and the anode are separated by the insulting covering which covers the anode. The working stage is provided for carrying the workpiece so as to allow the metal layer to face the anode and the cathode. The power supply has a positive electrode connected with the anode of the electroetching unit, and a negative electrode connected with the cathode. In addition, the electrolyte source supply is communicated with the insulting covering of the electroetching unit, and pours an electrolyte solution onto the anode and thereafter impinging upon the workpiece and passing through a passage defined by the workpiece and the anode.

TECHNICAL FIELD

The present invention generally relates to recycle a substrate and in particular to an apparatus and method for recycling the same by electrolytic etching and chemical stripping of a substrate surface. The present invention more specifically relates to the use of an electrolytic etching apparatus and method applied to remove metal materials from the surface of a metallic workpiece (i.e., a substrate) for patterning.

BACKGROUND OF THE INVENTION

In the microelectronics industry, semiconductor components are fabricated in a layer process which includes steps, such as spin coating or sputtering, to deposit organic layers and inorganic metal layers, namely an organic-inorganic composite sheet, onto a substrate surface. One such electronic component comprises the organic-inorganic composite sheet is a color filter substrate of a LCD panel, which includes a glass substrate 91 on which is coated with organic layers of a resin black matrix 92, a RGB photoresist 93 and an overcoat 94, and a metal layer of an ITO film 91 covered on the outmost, as depicted in FIG. 7.

Typically, semiconductor components are fragile and require a complicated manufacturing process which causes a low yield. Any problem such as particles, defective films, dislocation or high impedance may cause a defective substrate. These defective ones from the process, as well as household waste products, such as LCD wastes, have become serious environmental pollutants.

Various techniques are employed to recycle the defective workpieces, i.e., substrates, during processing so as to reduce the loss due to the low yield and to reduce the pollution of the environment. Two prior art techniques are found in Taiwan Pat. No. 546,264 and No. 546,265, which disclose chemical processes for recycling a defective Cr-BM color filter substrate and a defective Resin-BM color filter substrate respectively. The prior arts mainly describe the methods comprises the steps of dipping the defective color filter substrate into acidic etchants; brushing through the substrate surface and cleaning the same to obtain a reusable glass substrate with Cr-black matrix remained thereon according to No. 546,264 or a renewed mother glass substrate according to No. 546,265.

However, the acidic etchants strips not only the organic layers of the color filter substrate but also the metal layers thereof, which generates a poisonous waste liquid with heavy metal therein, thereby causes a secondary pollution. What is desired, therefore, is a recycling system and process which is not subject to the secondary pollution.

With respect to etching techniques for patterning of thin metallic films, the process of drying etching, wet etching or electroetching is widely employed. For examples of the uses of the electroetching process, see Taiwan Pat. No. I223350, and U.S. Pat. Nos. 5,284,554 and 6,103,554. These references all relate to the electrochemical micromachining of a sample. Wherein, the Taiwan Pat. No. I223350 discloses a completely submerged electroetching apparatus used for the electroetching of a relative large surface, in which a workpiece is served as anode and is connected to a positive electrode of a power supply, and an electrolyte solution is connected to a negative electrode of the power supply. In practice, however, a completely submerged electroetching system tends to pose certain problems including high power requirements. In order to alleviate such problems, the U.S. Pat. Nos. 5,284,554 and 6,103,554 each discloses an electroetching system which progressively treats only a small portion of the wafer to be etched. To this end, a multi-nozzle cathode assembly is provided which has a small width relative to the overall dimensions of the surface to be etched. This cathode assembly is then used to deliver the electrolyte to limited portions of the surfaces as the nozzle assembly is scanned across the surface of the wafer.

Heretofore the electrolytic etching techniques have been practiced by the workpiece (anode) in touch with the positive electrode terminal of the power supply, which poses many limits to an automated continuous process.

What is desired, therefore, is an electrolytic system for removing metallic material effectively and completely and for suitably applying to the automated continuous process.

SUMMARY OF INVENTION

It is therefore an object of this invention to provide an improved recycling system and method which can be used to recycle a workpiece without the secondary pollution.

It is another objective of this invention is to provide an improved electrolytic assembly and method for removing metal from the surface of the workpiece selectively and efficiently.

It is still another objective of this invention to provide an improved electrolytic assembly adapted to an automated continuous process.

To achieve these and other objects, the present invention provides a system for recycling a workpiece, comprising an electrolytic etching assembly for etching a metal layer of the workpiece. The electrolytic etching assembly has an electroetching unit, a working stage, a power supply and an electrolyte source supply. The electroetching unit has an anode, a cathode next to the anode and an insulting covering, wherein the cathode and the anode are separated by the insulting covering which covers the anode. The working stage is provided for carrying the workpiece so as to allow the metal layer to face the anode and the cathode. The power supply has a positive electrode connected with the anode of the electroetching unit, and a negative electrode connected with the cathode. In addition, the electrolyte source supply is communicated with the insulting covering of the electroetching unit, and pours an electrolyte solution onto the anode and thereafter impinging upon the workpiece and passing through a passage defined by the workpiece and the anode.

In this state, the electroetching unit of the electrolytic assembly is used to both deliver the electrolyte solution and scan across a surface, i.e. metal layer, of the workpiece, while contacting with the workpiece by neither the anode nor the cathode, so called “Contactless Electrolytic Etching Method”.

Preferably, the system further comprises a chemical stripping assembly for etching the organic layer of the workpiece. This means the present invention treats the metal layer and the organic layer separately; thereby cause not the secondary pollution when compared with the prior arts.

Preferably, the system further comprises a metal recycling unit for recycling a metal material of the metal layer, such as a noble metal, or for restoring the electrolytic solution.

Preferably, the system further comprises a waste treatment assembly for recycling an organic waste generated from the chemical stripping assembly.

A method of recycling a workpiece of an organic-inorganic composite sheet consistent with the present invention comprises steps of electroetching a metal layer of the workpiece; and chemically stripping an organic layer of the workpiece. Thus, it is possible to avoid the secondary pollution while recycling a substrate with an organic-inorganic composite film.

Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be elucidated by reference to the following description, appended claims, and accompanying drawings where

FIG. 1 is a block diagram shows a preferred embodiment of the recycling system of the subject invention;

FIG. 2 is a partial flow chart of FIG. 1, showing a electrolytic etching assembly and a metal recycling unit;

FIGS. 3A-3C are dynamical perspective views showing an electroetching unit and a working stage moving relative to each other;

FIGS. 4A-4B are examples of the electrolytic etching assembly;

FIGS. 5A-5B are examples of the anode according to another example of electrolytic etching assembly, showing different layouts of the anode;

FIG. 6 is a generalized flow sheet illustrating a preferred embodiment of the method of the present invention; and

FIG. 7 depicts a conventional color filter substrate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to FIG. 1, description will be made of a recycling system according to a preferred embodiment of this invention. The recycling system provided for recycling a workpiece having an organic-inorganic composite sheet comprises an electrolytic etching assembly 100, a chemical stripping assembly 200, a metal recycling unit 300, and a waste treatment assembly 400, wherein the electrolytic assembly 100 is mainly provided for electroetching a metal layer of the organic-inorganic composite sheet; the chemical stripping assembly 200 is for removing an organic layer of the organic-inorganic composite sheet from the workpiece; the metal recycling unit 300 is for recycling a metal material of the etched metal layer; and the waste treatment assembly 400 is used for recycling the organic waste generated from the chemical stripping assembly 200.

As can be seen from the FIG. 2, the recycling system is partly integrated with electrolytic etching assembly 100 and the metal recycling unit 300. The electrolytic etching assembly 100 mainly has an electroetching unit 1, a working stage 2, a power supply 3, and an electrolytic supply source 4. In a preferred embodiment, the electroetching unit 1 has an anode 10, two cathodes 11 and an insulting covering 12, wherein the two cathodes 11 and the anode 10 are separated by the insulting covering 12 which covers the anode 10. The two cathodes 11 are held by two fixing board 13 proximate to the insulting covering 12. One skilled in the art will appreciate that only one cathode 11 may be applied in this embodiment for the same purpose, whereas the two cathodes 11 are preferred for a better etching effect.

The working stage 2 is provided for carrying the workpiece 8 so as to allow the metal layer 81 of the workpiece 8 to face upwardly to the anode 10 and the cathodes 11. The power supply 3 has a positive electrode (presented by a plus sign) connected with the anode 10 of the electroetching unit 1, and a negative electrode (presented by a minus sign) connected with the cathodes 11, thereby provides power for the need of electrolysis. The electrolyte source supply 4 is communicated with the insulting covering 12 of the electroetching unit 1, and pours an electrolyte solution 41 onto the anode 10 and thereafter impinging upon the workpiece 8 and passing through a passage 14 defined by the workpiece 8 and the cathodes 11. In other words, the passage 14 is continuously filled with the electrolyte solution 41 in a steady state so that the anode 10, the cathodes 11 and the metal layer 81 get electrically connected together via the electrolyte solution 41. Accordingly, a specific portion of the metal layer 81, which sits directly underneath the anode 10, will be etched due to the electrolysis via the electrolytic solution 41 which pours from the anode 10. It should be understood that neither the anode 10 nor the cathodes 11 contact directly with the workpiece, which differs from those of the prior arts. The present invention is a pioneer in deploying the innovative “Contactless Electrolytic Etching Method”.

In order to act steadily without being corroded seriously, the anode 10 is made of an insert material, such as platinum or semiconductor materials. Furthermore, the anode 10 may be arranged to be capable of rotation in order to prolong a period of time. While rotating, outer peripheral surfaces of the anode 10 can be corroded lightly and evenly as time processes. Thus, the rotatable anode 10 can has a longer lift span when compared with the stationary one, and can perform a better, uniform etching effect.

In addition, either the electroetching unit 1 or the working stage 2 may be movable in a lateral direction in order that the electrolytic solution 41 can be impinged against the entire metal layer 81 by either moving the electroetching unit 1 laterally over the working stage 2, as depicted in FIG. 3A or by moving the working stage 2 laterally beneath the electroetching unit 1, as depicted in FIG. 3B if the electrolytic solution 41 does not impinge onto the entire metal layer 81 in a stationary mode. Alternatively, both the electroetching unit 1 and the working stage 2 move in a contrary direction to fulfill the same purpose, as depicted in FIG. 3C. The middle scenario, namely FIG. 3B, is preferable for applying to an automated continuous process. In other words, the Contactless Electrolytic Etching Method is advantageous in view of electrolytic etching assembly 1 to selectively etch a predetermined area of the workpiece 8. Operating under these conditions leads to a better surface finish and uniformity of metal dissolution when compared with the stationary mode.

Referring to FIG. 4A, the electroetching unit 1 further has a metallic member 101 disposed near an end of the insulting covering 12 and adjacent to the working stage 2 such that the metallic member 101 can be served as an extension of the anode 10. In this state, edges of the metal layer 81 of the workpiece 8 can be etched as well as the middle portions of the metal layer 81. In addition, the metallic member 101 may be connected to the positive electrode of the power supply 3 for a better etching effect.

Alternatively, as shown in FIG. 4B, the electroetching unit 1 may has a movable metallic part 102, instead of the metallic member 101 mentioned above. The movable metallic part 102 has an end disposed near an end of the insulting covering 12 and adjacent to the working stage 2, and another end extended inward of the insulating covering 12 and adjacent to the anode. In addition, the metallic part 102 is movable to simultaneously either contact with the workpiece 8 and the anode 10 or depart from the workpiece 8 and the anode 10. In this case, the movable metallic part 102 doesn't need to be electrically connected to the positive electrode of the power supply 3. Normally, the movable metallic part 102 is located in a higher position. When the edge of the metals is close to be etched, the movable metallic part 102 will be brought down to a lower position where the movable metallic part 102 can contact both the anode 10 and the metal layer 81. On the contrary, the movable metallic part 102 can be moved off the anode 10 and the metal layer 81 when the etching is finished.

Referring back to the FIG. 2, the cathodes 11 of the electroetching unit 1 is shaped as a plate and the anode 10 is shaped as a rod, thereby the cathodes 11 has a larger surface area facing toward the workpiece 8 than that of the anode 10 in order that a better etching performance can be obtained by a better current spreading or current distribution.

FIG. 5A is a top plan view of the electroetching unit 1 with respect to the workpiece 8, showing another example of the anode 10 a of the electroetching unit 1. The anode 10 a has a plurality of electrode rods 103 arranged as an array. Each of the electrode rods 103 has an end pointing toward the workpiece 8, thereby the electroetching unit 1 can intensively etch a specific projective area of the workpiece 8, onto where the plurality of electrode rods 103 project. It is noted herein that the anode 10 a as a whole has a size similar to the rod-shaped anode 10 and still smaller than the cathodes 11. Besides, each of the plurality of electrode rods 103 is perpendicular to the workpiece 8, which differs from the anode 10 parallel to the workpiece 8. Thus, the bottom end of the anode 10 a acts as an uniform working area to intensively etch the specific projective area of the workpiece 8. It is suitable for applying into a photolithographic and etching process in the semiconductor industry. This means the electrolytic etching assembly 100 can be used to substitute for drying etching or wet etching which is well known in the arts, and combine the benefits of high precision, high selectivity and low power consumption.

FIG. 5B shows another example of the array of the plurality of electrodes 103 of the anode 10 a. The plurality of electrodes 103 is arranged as a visual pattern so as to transfer the visual pattern to the specific projective area of the workpiece 8 via electroetching. For instance, when the array 10 a is presented as a word “I-L-U” as depicted in FIG. 5B, the corresponding projective area will be intensively etched to represent the word “I-L-U” thereon after electrolysis.

Referring back to FIG. 2, the electrolytic etching assembly 100 further has a reservoir 5 placed under the working stage 2 for collecting the used electrolyte solution 41 for metal recycling. Typically, the metal recycling unit 300 of the recycling system mainly includes a selective smelter 40, a filtration unit 21, a settling tank 22 and an electroplating assembly 30.

Referring back to FIG. 1, when a DC bias is applied to the electrolytic etching assembly 100, the metal layer 81 of the workpiece 8 will be electrolyzed and dissolve into the flowing electrolyte solution 41. Such a reaction, for example, is represented as follows:

Oxidation reaction of the metal layer 81: M→M ^(+Z) +z e ⁻

In the meantime, a portion of the metal ions dissolved in the electrolyte solutions 41 are herein reduced into metal atoms, namely the electroplated metals, and deposited onto a side of the cathodes 11. Such a reaction, for example, is represented as follows:

First reduction reaction: (a portion of the metal ions) M ^(+Z) +z e ⁻ →M

Next, a worker can easily take out the electroplated metals from the side of the cathodes 11 by using a scraper and bring to the selective smelter 4 which is capable of melting and separating a first metal (M1) from electroplated metals. Take the color filter substrate as an example, the Indium metal has a lower melting point (156.60° C.) than that of the Sn metal (231.91° C.) so that the Indium metal can be melted out first to separate from the Sn metal.

Another portion of the metal ions dissolved in the electrolyte solutions 41 is drained out from the reservoir 5 and is passed to the filtration unit 21 which is provided for purifying the used electrolyte solution 41 by a filter material thereof, and then is passed to the settling tank 22 where particles suspended in the electrolyte solution 13 are allowed to sink to the bottom of the reservoir 5 for another purification. Accordingly, after the double purification by the filtration unit 21 and the settling tank 22, the clean electrolyte solution 41 containing the other portion of the metal ions is derived.

Next, the clean electrolyte solution 41 may be brought into the electroplating assembly 30 which is capable of applying a specific bias voltage to educe a second metal (M2) from the clean electrolyte solution 41. The general chemical reaction herein is the same with the first reduction reaction happened in the electrolytic etching assembly 100 and is herein presented again as:

Second reduction reaction: (another portion of the metal ions) M ^(+Z) +z e ⁻ →M

As depicted in FIG. 2, the electroplating assembly 30 may has a plurality of electrodes so as to apply different bias voltages to generate different electroplated metals in a time as a result of each kind of metal having a specific chemical property different from others. Take a color filter as an example, when the plurality of electrodes 30 a, 30 b, 30 c are supplied with different bias voltages 3.0 v (smaller than 3.5 v), 3.5 v, and 4 v (larger than 3.5 v), Tin (Sn), Chromium (Cr) and Indium (In) will be simultaneously deposited on the respective electrodes 30 a, 30 b, and 30 c respectively.

After the metal ions are taken out from the electrolyte solution 41 by electroplating, the electrolyte solution 41 which contains no or less metal ions can be either returned back to the electrolytic etching assembly 100 by a conduit 17, as shown in FIG. 2, or stored in another tank 31 for later treatment.

In order to purify the first metal (M1) and the second metal (M2), which are specially made of the same chemical element, such as a noble metal Indium, and are respectively generated from the cathode 11 of electrolytic etching assembly 100 and the electroplating assembly 30, the recycling system further comprises a refining furnace 50 for using heat to refine the metals M1 and M2 to a ultra-pure metal.

In the foregoing description, the electrolytic etching assembly 100 is used to etching the metal layer 81 of the workpiece 8 so as to recycle a reusable workpiece. And, the metal recycling unit 300 is used to recycle the metal materials of the metal layer out of the electrolyte solution 41 without causing the secondary pollution. It should be noted that the recycling system has the benefit to recycle any workpiece with a metal layer, without limits to a workpiece having both a metal layer and an organic layer, namely an organic-inorganic composite sheet.

Moreover, the chemical stripping assembly 200 of recycling system is provided for stripping the organic layer (not shown) of the workpiece 8 by using an alkaline solution, such as a Sodium Hydroxide solution, unlike a concentrated acid solution used by the prior art. The concentrated sulfuric acid can etch not only organic layers but also metal layers. However, it is to be understood that the chemical stripping assembly may still use the acid solution to strip the organic layer only if the workpiece 8 has been checked to have no metal components thereon. Thus, in the recycling system according to the present invention, the metal layer and the organic layer are processed separately in order to avoid generating toxic heavy metal contaminated waste water which causes the secondary pollution.

Referring yet again to FIG. 1, the waste treatment assembly 400 of the recycling system has an ozone generator 51 and a store tank 52. The ozone generator is provided for decomposing organic waste generated from the chemical stripping assembly 200. Under heating condition, the waste treatment assembly 400 can pump ozone generated by the ozone generator 51 into the store tank 52 where the organic waste stored to decompose the organic waste into small molecules, such as H₂O or CO₂. Accordingly, the organic waste can be purified to a clean solution containing no poisonous components so as to be recycled and reused.

As noted above, the recycling system of the present invention uses the electrolytic etching assembly 100 and the chemical stripping assembly 200 to process the metal layer and the organic layer respectively so as to recycle the reusable workpiece. More particularly, the recycling system further uses the metal recycling unit 300 to recycle the metal materials and the electrolyte solution, and uses the waste treatment assembly 400 to treat the organic waste. These make the recycling system of the present invention the most ideal and environment-friendly system ever conceived.

Referring to FIG. 6, a method for recycling a workpiece of an organic-inorganic composite sheet in accordance with a preferred embodiment of the present invention comprises steps of electroetching 70 a metal layer of the workpiece by dissolving the metals of the metal layer into an electrolyte solution, and chemically stripping 71 an organic layer of the workpiece by dipping the workpiece into a chemical etchant as mentioned above. It is noted herein that the method of the electroetching 70 is not limited to the Contactless Electrolytic Etching Method; a conventional electrolytic etching method is also suitable for this step 70.

As for the sequence of the steps, it depends on which kind of layer is at the topmost of the workpiece 8 in consideration of environment protection. If the metal layer is on the top, the electroetching 70 is preferred to be performed first than the chemical stripping 71. On the contrary, if the organic layer is covered on the topmost, it is better to perform the step of the chemical stripping 71 first.

Next, the method further comprises steps of collecting 73 an electrolyte solution generated by electroetching 70; electroplating 75 a first metal 77 from the electrolyte solution; collecting 74 electroplated metals generated by electroetching 70; and smelting 76 the electroplated metals to separate a second metal 78 from the electroplated metals.

Suppose that the first metal 77 and the second metal 78 are noble metals made of the same chemical element, the method may further comprising steps of refining 79 the first metal and the second metal so as to return the metals 77, 78 into a ultra-pure metal.

Moreover, the method further comprises a step of applying ozone, or UV radiations to decompose 72 organic waste generated by the chemical stripping 71. Accordingly, the organic waste may be transformed into a clean solution for recycling without polluting the environment.

Thus, the recycling system and method of the present invention is the most ideal, and environment-friendly system ever conceived.

Numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in appended claims. The disclosure, however, is illustrative only, and changes may be made in detail, especially, in matters of shape, size and arrangement of parts, materials and the combination thereof within the principle of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A recycling system comprising: an electrolytic etching assembly for etching a metal layer of a workpiece having: an electroetching unit having an anode, a cathode and an insulting covering, wherein the cathode and the anode are separated by the insulting covering which covers the anode; a working stage provided for carrying the workpiece so as to allow the metal layer to face the anode and the cathode; a power supply, having a positive electrode connected with the anode of the electroetching unit, and a negative electrode connected with the cathode; and an electrolyte source supply, communicated with the insulting covering of the electroetching unit, and pouring an electrolyte solution onto the anode and thereafter impinging upon the workpiece and passing through a passage defined by the workpiece and the anode.
 2. The recycling system of claim 1, wherein the anode of the electroetching unit is made of an insert electrode material.
 3. The recycling system of claim 2, wherein the anode of the electroetching unit is capable of rotation.
 4. The recycling system of claim 1, wherein either the electroetching unit or the working stage can move relative to each other.
 5. The recycling system of claim 4, wherein the electroetching unit further having a metallic member disposed near an end of the insulting covering and adjacent to the working stage.
 6. The recycling system of claim 4, wherein the electroetching unit further having a movable metallic part which has an end disposed near an end of the insulting covering and adjacent to the working stage, and another end extended inward of the insulating covering and adjacent to the anode, and is movable to simultaneously either contact with the workpiece and the anode or depart from the workpiece and the anode.
 7. The recycling system of claim 1, wherein the anode of the electroetching unit is shaped as a rod; and the cathode is shaped as a plate.
 8. The recycling system of claim 1, wherein the cathode of the electroetching unit has a larger exposed area facing toward the workpiece than that of the anode.
 9. The recycling system of claim 8, wherein the anode of the electroetching unit has a plurality of electrode rods arranged as an array, each having an end pointing toward the workpiece, thereby the electroetching unit can intensively etch a specific projective area of the workpiece, onto where the plurality of electrode rods project.
 10. The recycling system of claim 9, wherein the array of the plurality of electrodes is arranged as a visual pattern so as to transfer the visual pattern unto the specific projective area of the workpiece via electroetching.
 11. The recycling system of claim 1, further comprising a selective smelter capable of melting and separating a first metal from electroplated metals deposited on a side of the cathode of the electroetching unit.
 12. The recycling system of claim 1, further comprising an electroplating assembly capable of applying a specific bias voltage to educe a second metal from the electrolyte solution coming of the electrolytic etching assembly.
 13. The recycling system of claim 12, wherein the electroplating assembly has a plurality of electrodes so as to apply different bias voltages to generate different electroplated metals.
 14. The recycling system of claim 12, further comprising a refining furnace for purifying the second metals.
 15. The recycling system of claim 1, further comprising a chemical stripping assembly for stripping an organic layer of the workpiece.
 16. The recycling system of claim 15, further comprising an ozone generator for decomposing organic waste generated from the chemical stripping assembly.
 17. A method for recycling a workpiece of an organic-inorganic composite sheet comprising steps of: electroetching a metal layer of the workpiece; and chemically stripping an organic layer of the workpiece.
 18. The method of claim 17, further comprising steps of: collecting an electrolyte solution generated by electroetching; electroplating a first metal from the electrolyte solution; collecting electroplated metals generated by electroetching; and smelting the electroplated metals to separate a second metal from the electroplated metals.
 19. The method of claim 18, further comprising steps of refining the first metal and the second metal.
 20. The method of claim 17, further comprising a step of applying ozone to decompose organic waste generated by the chemical stripping. 